1. Field of the Invention
The invention relates to a method for processing a mixture of material, in particular for processing a mixture of material which contains at least one coarse component in pieces and one fine component, and to an apparatus for performing the method of the invention.
2. Related Art
Material that contains such coarse components as stones, relatively small pieces of rock or the like, as well as a fine component that adheres or sticks to the coarse component depending on its moisture content, is often processed into other products worth using by separating the components of the material from one another. In practice, both the composition of the starting mixture of material and its moisture content vary considerably from one case to another. Furthermore, such materials often stubbornly resist simple separation. If the fine component adheres to the coarse components, the mixture of material cannot be separated in a screening operation. Even with so-called roller grates, the material in many cases cannot be readily separated. The fine component may cause a cake to form that does not pass through the openings between the driven rollers, and so adequate separation of stones and fine material is not achieved. However, if chisels or other profiled features are provided on the individual rollers of the roller grates, these chisels or features being intended to feed the fine component downward between the driven rollers, then problems can arise with the coarse component, that is, the stones or pieces of rock contained. For material separation, washing methods are therefore often employed, which wash the fine component out of the coarse component in the form of a sludge. However, the sludge is usually not re-usable, so that there are high subsequent costs for disposing of it. Moreover, the high water consumption often stands in the way of economical employment of such methods. Finally, only one part of the starting material, such as the coarse part, is actually used.
From German Patent DE 196 27 465 C2, it is known to use so-called bucket separators for separating material. They are embodied on the order of a dredge or excavator bucket, with at least two driven rollers disposed in the bottom of the bucket. Disks and chisels are disposed on the rollers. For material processing, the mixture of material is picked up with this bucket, and the bucket is pivoted such that the material it contains weighs down on the rollers. As a result of their rotations, the rollers let the fine component drop through between them, while the coarse component remains in the bucket separator and can then be tipped out.
It is also known from DE 196 27 465 C2 to add added material to the material picked up by the bucket separator; a defined portion of this added material is for instance taken from an appropriate silo and then rests on the picked-up material in the bucket separator. The added material is fed along with the fine component through the bucket separator and separated from the coarse component. Initially, approximately ⅓ of the picked-up material is fed through the bucket separator without added material. To achieve complete mixing of the added material and the fine component, it is necessary as a rule for the finer material that is discharged from the bucket separator to be picked up again by the bucket and made to pass between the rollers. This operation may have to be repeated several times.
From German Patent DE 199 25 502 C1, a method for recovering oil from drilling sludge and/or oil-containing drilling sludge fractions is also known. In this method, coal dust is added to the drilling sludge. Next, the resultant suspension is mixed, after which the mixture is divided into a lightweight and a heavy fraction of coal dust and oil. The coal dust and oil fraction is then separated out by desorption or extraction.